My parents have DirecTIVO, and I think thats pretty awesome
2 HD DirecTIVO + one non-HD DirectIVO connected to the slingbox for me to watch games not on TV where I am FTW
$6/month, no extra charge for multiple DirecTIVOs (beyond what DirecTV charges for each additional receiver)
Of that $6/month, I bet TiVo themselves gets no more than $4..but if we had regular DirecTV boxes plus additional TiVo units, not only would the usage be more clunky, we would be looking at $20+$14+14= $38/month just for DVR! outrageous..